Unless otherwise indicated herein, the approaches described in this section are not prior art to the claims in this application and are not admitted to be prior art by inclusion in this section.
Sound travels through solid, liquid or gas medium as an oscillation wave of pressure. Unlike light, sound cannot travel through a vacuum. When a sound has a frequency that is within a specific range and has a sufficiently strong intensity, the vibration that is caused by sound traveling through the medium may be detected by a human or device. The intensity of sound decreases during propagation as the traveling distance increases. Other factors may cause the decrease of the sound intensity include the dissemination of sound waves and the scattering of the sound waves due to obstacles. Also, a part of the acoustic energy of the sound wave may be absorbed by the medium that the sound wave is passing through. This phenomenon is often referred to as acoustic absorption or attenuation. Additional factors, such as viscosity, thermal conduction, or micro-relaxation absorption may also cause attenuation.
The intensity of the sound at a particular location along the sound-wave propagation path may be measured by evaluating the sound pressure that is detected by a sound sensor. The sound sensor may be configured to monitor and measure the characteristics of the sound wave, such as velocity, frequency, and/or phase, and any changes to such characteristics. The sound sensor may generate a signal indicating the amount of sound pressure detected. The sound pressure signal may then be used to further determine the existence and the volume of the sound.